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Fukushima Meltdown Update: More Problems at Number 4

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More Problems at Fukushima: January 15 Update
by Nelle Maxey
Two more problems (aside from the Unit #4 mystery which I update below) have surfaced in the last week at the Fukushima plant site.

First, a temperature sensor in Unit 2 is recording increasingly high temperatures at the bottom of the Reactor Pressure Vessel (RPV) in the control rod drive housing which hang below the RPV inside the Primary Containment Vessel (PCV). Unit 2 is the Unit that did not explode and damage the building as did Unit 1, 3, and 4 in March. However, there was an explosion in the torus which has been both reported and denied by TEPCO.
 
More mysteries. This is also the reactor TEPCO announced they were planning to drill into and insert a scope to look at the state of the PCV in January. No word on this activity so far however.

Ex-SKF reports here on  the temperature sensor in Unit 2.

#Fukushima I Nuke Plant Reactor 2: 116 Degrees Celsius at the RPV Bottom
Some "cold shutdown". But you see, the thermometer that "determines" the state of cold shutdown is not this particular one that exceeded 100 degrees Celsius. So everything is fine and dandy at Fuku I. (Forget the leaks here and there, and trenches full of contaminated water.)

From Kyodo News (1/13/2011): [Japanese text removed]

  TEPCO announced on January 13 that one of the thermometers near the bottom of the Reactor Pressure Vessel of Reactor 2 at Fukushima I Nuclear Power Plant registered the temperature exceeding 100 degrees Celsius. The nearby thermometers show a steady temperature between 40 to 50 degrees Celsius, so TEPCO considers it as malfunctioning.

  According to TEPCO, the thermometer that showed the high temperature is the one attached to the pipe that contains the equipment to operate control rods. It was 48.4 degrees Celsius at 5PM on January 12. It rose sharply at 11PM to 102.3 degrees Celsius, and at 5AM on January 13 it registered 116.4 degrees Celsius.

  The thermometer that measures the temperature at the bottom of the RPV shows stable 48 degrees Celsius. That measurement is used as determining the cold shutdown state. TEPCO thinks it is unlikely that the melted fuel has shifted or the recriticality is happening.

Nelle’s comment on this story (which also appeared on ENENews and various other blog sites):

I have been following the daily TEPCO temperature data for Units 1, 2, 3 for months. Scroll down to the “parameters” section here and you can download the pdfs: http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html#anchor02

You can directly access today’s TEPCO temperature data sheet pdf for Unit 2 which here: http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/12011512_temp_data_2u-e.pdf

I have taken snapshots of this document below. On page 1 you see a line chart showing temperature readings and a diagram of the Reactor Pressure Vessel (RPV) showing locations of temperature measurements. The one we are interested in are the brown-colored triangles which reflect the temperature at the top of the Control Rod Drive (CRD) Housing in this chart and diagram.

Note the very high temperatures this sensor recorded in both March during the accident and in May. The brown triangles go off the chart. Then in the center of the chart you see lower but still volatile temperatures from mid-June thru mid-September when the brown line begins dropping with a small rise at the beginning of September and then a continued drop of temperature until the sudden increase this week.

During none of the earlier temperature swings did TEPCO announce that the CRD Housing temperature sensor was malfunctioning. Nor did they say that the bottom of the RPV (the green line) was cooler than the CRD, so everything must be okay, as the article above reports.

As you can see on the chart, sometimes the bottom of the RPV (green line) was lower than the CRD Housing temperature especially during the period of meltdowns in the spring and then up until mid-September. But once the reactor was stabilized, the CRD Housing was cooler than the bottom of the RPV. That is, until this week. Now they announce the sensor is malfunctioning. For the above reasons, I find their assurances of questionable value. (BTW, there is no way they can access this sensor to check it or change it out due to the high radiation levels in the reactor building and especially in the reactor itself.)


The second page of the pdf gives the temperature readings in chart form. I’ve clipped the chart to the relevant information which are the last two columns in the chart. As you go down to the most recent readings you see they are volatile (as they were earlier in the summer). but also escalating. The last reading is for 138.5 degrees Celsius. This definitely bears watching.

The second problem has to do with new leaks of contaminated water from all of the Units this week.

I don’t know if these leaks have to do with winter weather temperatures or simply the breaking down of the plastic piping and the metal tanks from their exposure to the highly contaminated water. But it is not good news as the decontamination of the highly contaminated water was one of the main issues in their roadmap to control radiation contamination.  

http://mdn.mainichi.jp/mdnnews/news/20120113p2g00m0dm020000c.html

(Mainichi Japan) January 13, 2012

300 tons of tainted water found near No. 3 unit at Fukushima plant

  TOKYO (Kyodo) -- Around 300 tons of water contaminated with relatively high amounts of radioactive substances has been found in an underground tunnel near the No. 3 unit at the crippled Fukushima Daiichi nuclear power plant, the plant's operator said Thursday.

  Tokyo Electric Power Co. said the water in the tunnel, used to lay electric cables, contained 49 to 69 becquerels of radioactive cesium per cubic centimeter, adding that it will check how the contaminated water accumulated in the area.

  Some water with lower concentrations of radioactive materials was also found in a tunnel near the No. 1 unit.

  The utility known as TEPCO is checking for accumulated pools of water in underground tunnels at the plant after around 220 tons of contaminated water was found on Dec. 18 in a tunnel near a facility on the plant premises for storing highly contaminated water.

  On Wednesday, contaminated water was found to have accumulated in two underground tunnels.

This newspaper report followed  this handout from TEPCO showing the locations of the leaks:

The second page of the handout contains this chart of leaks “discovered” on Jan 11 and 12:

You can see the original here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120113_02-e.pdf

These leaks are in addition to one reported on January 11th in the holding tank for the desalination unit: http://enformable.com/2012/01/fukushima-daiichi-water-leakage-beta-radiation-levels-magnitudes-greater-than-cesium/

Here is an Update on the mystery at Unit 4. Ex-SKF reports a tweet on a government official’s site regarding an “explosion” at Unit 4 on Jan 9th. He uses the words “baseless rumor” in the headline in a satirical manner as this is a phrase repeated often by government regarding bad news about the accident:

"Baseless Rumor" from an LDP Upper House Politician: Explosion in Fukushima I on January 9?
  Satsuki Katayama is an LDP member of the Upper House of the Japanese Diet and a former career bureaucrat in the Ministry of Finance.

  In her official blog on January 13, 2012, Katayama relates the following rumor: [Japanese text removed]


    Just then, there was a communication from the ex-council member of Minami Soma City to the mayor [of Soma City] that there was some kind of explosion at Fukushima I Nuclear Power Plant on January 9 (probably at Reactor 4 building) and the government is hiding it. I don't know whether it's true or not, but if it is, it is probably a hydrogen explosion, not a nuclear explosion.

  Katayama says she was speaking with Hidekiyo Tachiya, mayor of Soma City (north of Minami Soma City) when the mayor related the "rumor" to her. I have no idea why she's allowed to talk loose like this in her official blog. 

  So far, it doesn't seem to have gathered much attention in Japan, and many on Twitter ridicule her. But some people are connecting this "rumor" to the massive deployment of the Self Defense Force helicopters on January 9.

source: http://ex-skf.blogspot.com/2012/01/baseless-rumor-from-ldp-upper-house.html

The plot thickens.

 

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